Systems and methods for deploying a luminal prosthesis over a Carina

ABSTRACT

A system for deploying a prosthesis over a Carina between an ipsilateral lumen and a contralateral lumen includes a guidewire, a guidewire capture catheter, a self-expanding tubular prosthesis, and a delivery catheter. The guidewire is first placed in the ipsilateral lumen. The guidewire capture catheter is then advanced from the contralateral lumen to a position at or above the ipsilateral lumen. The guidewire is typically advanced through an occlusion, which may be a total occlusion, and captured by a capture element on the guidewire capture catheter. The guidewire capture catheter pulls the guidewire out through the contralateral side, and the guidewire is used to advance a delivery catheter from the ipsilateral side. The delivery catheter delivers a first segment of the tubular prosthesis in the ipsilateral lumen and a second segment of the prosthesis in the contralateral lumen.

CROSS-REFERENCE

This application is a continuation of U.S. patent application Ser. No.15/472,107, filed Mar. 28, 2017, which is a continuation of U.S. patentapplication Ser. No. 14/491,464, filed Sep. 19, 2014, now U.S. Pat. No.9,636,242, which claims the benefit of provisional application61/880,033, filed on Sep. 19, 2013, and of provisional application61/887,185, filed on Oct. 4, 2013, the full disclosures of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to medical systems and methods.More particularly, the present invention relates to systems and methodsfor stenting aortic and other bifurcations while preservingcontralateral arterial access.

The use of endoluminal prostheses for treating vascular and otherdiseases has become wide-spread over the past several decades.Endoluminal prostheses, commonly known as stents, are used to maintainthe patency of blood vessels and other body lumens. Stents are typicallyformed as tubular metal scaffolds which can be expanded in situ from arelatively small diameter to a larger diameter sufficient to maintainthe desired level of patency. The stents or other vessel scaffolds canbe covered with fabrics or membranes, in which case they are commonlyreferred to grafts.

The use of both stents and grafts has become wide-spread and hasrevolutionized many medical treatments. Despite the wide success, thetreatment of certain anatomies still presents challenges. For example,the treatment of atherosclerotic lesions in bifurcated blood vessels,where a main vessel divides into two branches, can be difficult. Forexample, occlusive disease frequently occurs at the bifurcation of theaorta into the iliac arteries. While such bifurcation disease may besuccessfully treated by using a pair of vascular grafts where one graftis placed in each iliac artery and the grafts are disposed side-by-sidein the aorta (commonly referred to as “kissing stents”), such treatmentmakes subsequent contralateral access to treat future disease moredifficult.

Referring to FIGS. 1A and 1B, the nature of occlusive disease whichoccurs at the bifurcation of an aorta A into an ipsilateral iliac arteryIIA and a contralateral ipsilateral artery CIA will be described. Theocclusive disease may be only partial, as illustrated in FIG. 1A, wherethe lumen of neither the ipsilateral nor the contralateral iliacarteries is fully occluded. In other cases, as illustrated in FIG. 1B,at least one of the ipsilateral and contralateral iliac lumens will becompletely blocked, referred to as a chronic total occlusion CTO.Treatments for these two different conditions will vary, as described indetail below in connection with the present invention. Presently,however, for both conditions the most common treatments is the placementof an ipsilateral stent or graft IS in the ipsilateral iliac artery IIAand a contralateral stent or graft CS in the contralateral iliac arteryCIA, as shown in FIG. 2 (the so-called kissing stents referred toearlier). While the resulting stent or graft structures provideexcellent recanalization of the aorta and the branching iliac arteries,the structure also makes it very difficult to achieve subsequentcontralateral access from an ipsilateral iliac artery. Without the stentor graft structures in place, it will be appreciated that a guidewireplaced in through an ipsilateral iliac artery can be easily passed overthe carina C into a contraleteral iliac artery once the occlusivedisease has been penetrated or bypassed. The “kissing stents” IS and CS,in contrast, form a boundary between the iliac arteries that makes itvery difficult to advance a guidewire from the ipsilateral iliac arteryIIA to the contralateral iliac artery CIA. Thus, subsequent treatment ofdisease at or near the aortic bifurcation can be much more difficult,often requiring open surgery rather than an endoluminal treatment.

For these reasons, it would be desirable to provide improved systems andmethods for treating occlusive and other disease at the aortic and othervascular and non-vascular vessel bifurcations. The systems and methodsshould be able to provide the improved patency achieved by the “kissingstents” of the prior art, while preserving the ability to subsequentlyaccess a contralateral lumen from an ipsilateral lumen by advancing aguidewire over the carina with minimum inhibition. The methods andsystems should be compatible with both totally and partially occludedlumens, and in the case of aortic disease, it should facilitate passageof a guidewire through a totally occluded ipsilateral iliac artery intoa contralateral iliac artery. At least some of these objectives will bemet by the inventions described below.

2. Description of the Background Art

Systems and methods for manipulating guidewires and bypassing occlusionsin the peripheral vasculature are described in US20140142677;US20140142677; US20070173878; US20030236566, US20030236566;US20040148005; US20030161901, US20060047222; US20080065019.

SUMMARY OF THE INVENTION

A principal objective of the present invention is to provide a stentingor grafting structure at an aortic or other bifurcation which iseffective to treat occlusive or other disease on either side of thecarina in the adjacent branch lumens without blocking or inhibitingsubsequent guidewire access from an ipsilateral lumen to a contralaterallumen over the carina. As illustrated in FIG. 3 , a tubular prosthesisstructure can, according to the present invention, cover the occlusivedisease and maintain luminal patency in the adjacent iliac arteries IIAand CIA on either side of the carina C, while maintaining a region orvolume above the carina substantially free from structures which wouldinhibit passage of a guidewire over the carina. In particular, thetubular prosthesis structures of the present invention will avoidcreating a wall or other barrier between the iliac arteries as wascharacteristic of the “kissing stents” shown in FIG. 2 above.

The following paragraphs define a glossary of terms and phrases whichare used in the specification and claims herein. Terms and phrases whichare not specifically defined herein will have the meanings normallyassociated with those terms and phrases to one of ordinary skill in theart of endovascular and endoluminal procedures, particularly includinginterventional radiologists and interventional cardiologists who performstenting and grafting procedures in the peripheral vasculature.

The phrases “ipsilateral lumen” and “contralateral lumen” will includeall vascular and other lumens which branch from a main or a primaryvessel or lumen. Of particular interest to the present invention, theaorta branches into a pair of common iliac arteries which subsequentlybranch into the internal iliac artery, the femoral artery, the poplitealartery, and the like. When the present application refers to introducinga guidewire or catheter into the iliac or any other lumen, thatintroduction can take place in the noted lumen or in any lumen which isdownstream from the noted lumen. In particular, introduction of aguidewire or catheter into the iliac artery will frequently be made viathe femoral artery. The designation of ipsilateral lumen andcontralateral lumen is somewhat arbitrary. For example, either of theiliac arteries may be designated as the ipsilateral iliac artery, inwhich case the other iliac artery becomes the contralateral iliacartery. For convenience, as used hereinafter, the ipsilateral lumen orartery will be that lumen into which a crossing guidewire is initiallyplaced and the contralateral lumen or artery will be the lumen intowhich the crossing guidewire is guided and exits the vasculature.

The phrase “luminal prosthesis” refers to any stent or graft structurewhich is placed over a carina to treat occlusive or other diseasespresent in either or both of the iliac arteries or other branchingvessels. The luminal prostheses will have a first segment configured tobe placed in an ipsilateral lumen and a second segment configured to beplaced in a contralateral lumen. The first and second segments willpreferably be coupled to each other in such a way that they may bedelivered in a straightened or linearized manner, and subsequently bentor folded over the carina in situ to assume their desired positioning invasculature or other lumens. In some cases, however, it will be possibleto deliver first segments which are not coupled and which areindependently anchored at their target locations in the branchinglumens.

The luminal prostheses of the present invention will preferably beself-expanding. By “self-expanding” it is meant that the prostheses,which are typically tubular in geometry, may be crimped or constrainedto assume a low diameter configuration, typically by placing over adelivery catheter within a constraining, outer sheath. The sheath isretractable, and once the constraint of the sheath is removed, theluminal prosthesis will be able to radially expand due to its ownresilience to open within the target vessel and provide the desiredsupport or scaffolding of the vessel. Such self-expanding luminalprostheses are typically formed from a resilient metal, such asnickel-titanium alloy (e.g., Nitinol®) but could also be other shapememory metals or a resilient polymer.

On treating a chronic total occlusion, it will often be necessary to“subintimally” advance the guidewire past the occlusion. Such“subintimal advancement” means that the guidewire passes out of thevascular or other vessel lumen into the region between the vascular walland the intimal tissue. The virtual space between these layers, whichare typical of the arterial vasculature, provides an advancement pathwhich bypasses the occlusion. It is necessary that, once past theocclusion, the guidewire be passed or directed back into the vessellumen. In some cases, the present invention can use conventionalguidewire advancement systems, such as the Pioneer® system availablefrom Volcano. Preferably, however, return of the subintimally advancedguidewire into the iliac or aorta (or other vasculature ornon-vasculature) lumen will be accomplished by a guidewire capturecatheter which is described and claimed herein.

The guidewire capture catheter will employ an expandable guidewirecapture element which is typically a mechanically expanded cage. Themechanically expanded cage can be a braided structure, a malecotstructure, or any other structure which may be expanded by axialforeshortening, electrical stimulation, pull-back using a pull-wire or acord, rotation using a screw or other mechanism, or the like. In otherless preferred cases, the cage may be self-expanding where it isinitially constrained within a sheath or other overlying element andreleased to radially expand when desired. In still other cases, theexpandable guidewire capture element can be actuated by an inflatableballoon, typically in combination with a wire cage or lattice structureover the balloon to provide a desired expansion force and guidewirecapture capability.

In a first aspect of the present invention, a method for deploying aluminal prosthesis over a carina between an ipsilateral lumen and ancontralateral lumen comprises placing a guidewire over the carinabetween the two lumens. A delivery catheter is advanced over theguidewire and carries the luminal prosthesis, typically a tubularprosthesis, over the carina. The prosthesis is deployed from thedelivery catheter so that a first segment of the prosthesis ispositioned in the ipsilateral lumen and a second segment of theprosthesis is positioned in the contralateral lumen. The ipsilaterallumen is typically an ipsilateral iliac artery, and the contralaterallumen is typically a contralateral iliac artery. In specificembodiments, the guidewire is placed initially through an ipsilateralfemoral artery, and then through the ipsilateral iliac artery and overthe carina, where it passes through the contralateral iliac artery andexits through the contralateral femoral artery.

In exemplary embodiments, placing the guidewire comprises advancing theguidewire through the ipsilateral lumen, over the carina, and into thecontralateral lumen. In cases where the ipsilateral lumen has a totalocclusion near the carina, and particularly in the case of anipsilateral iliac artery, the guidewire will be advanced through thesubintima past the total occlusion in the ipsilateral lumen, prior tobeing advanced over the carina and into the contralateral lumen. In suchcases, a guidewire capture catheter is preferably deployed through thecontralateral lumen to position a capture element above an opening ofthe ipsilateral lumen adjacent the carina. As the guidewire exits thesubintima, the capture element both deflects the guidewire back into thevessel lumen and captures the guidewire. By capturing the guidewire, theguidewire capture catheter can then be used to draw the guidewire outthrough the contralateral lumen and usually further out through theaccess sheath into the contralateral lumen.

Deploying the capture element typically comprises expanding the captureelement, and the capture element will typically be collapsed over theguidewire in order to capture the guidewire and prior to retracting theguidewire from the lumen or vasculature. The capture element maycomprise a cage structure, a balloon structure, or any of the mechanismspreviously described.

The tubular prosthesis is typically self-expanding and is constrained ina low profile or low diameter configuration on the delivery catheterprior to deployment. Deployment typically comprises retracting anoverlying sheath which releases the self-expanding prosthesis fromconstraint so that it may radially expand at a desired target site inthe iliac or other vascular or non-vascular lumen. Preferably, deployingthe prosthesis will further comprise the aligning markers on the tubularprosthesis and/or the delivery catheter with specific patient anatomy,usually under fluoroscopy, to position the first segment in theipsilateral lumen and the second segment in the contralateral lumenprior to deploying the prosthesis, typically by retracting the sheath.

Retracting the sheath may comprise retracting a single sheath in onedirection to sequentially release the first and second segments of thetubular prosthesis in a generally conventional manner for the release ofself-expanding prostheses. Alternatively and preferably, the sheath maycomprise first and second portions or lengths which cover the first andsecond segments of the tubular prostheses, respectively. The first andsecond lengths of the sheath may then be retracted into the ipsilateraland contralateral lumens, respectively, in order to separately releasethe first and second segments of the tubular prostheses. The first andsecond lengths of the sheath may be retracted simultaneously orsequentially, and in both cases the ability to separately deploy thefirst and second segments of the tubular prosthesis provides advantages,particularly permitting better placement by allowing each segment to bepartially deployed prior to full deployment of either segment.

The first and second segments of the tubular prosthesis are preferablydeployed to “tent” over the carina but to open from each other above thecarina to define and open, arcuate path between the ipsilateral andcontralateral lumens to allow subsequent advancement of the guidewireand/or treatment catheter. While a number of specific prosthesis designscan achieve this objective, it is advantageous that the particularprosthesis designs have little or no structure which would impedeadvancement of the guidewire or catheter over the carina. In exemplarydesigns of the tubular prostheses of the present invention, the firstand second segments may be joined by a hinge region, by a tether, or inother less preferable embodiments may not be joined at all. In stillother embodiments, the tubular prosthesis may be a generally continuoustubular structure where the first and second segments are defined by aside or lateral opening in the tubular prosthesis which expands as thetubular prosthesis is folded or bent over the carina. The opening orfenestration in the stent will preferably have a diameter equal to atleast the radius of the stent and could have a diameter equal to thediameter of the stent, or be even larger. By placing the opening orfenestration on the outside of the arc which is formed as the prosthesisis bent over the carina, the opening will significantly expand toprovide the open volume, free from structure, over the carina which isdesired.

In a second aspect of the present invention, a tubular prosthesis forplacement over a carina, between an ipsilateral iliac artery and acontralateral iliac artery comprises a first segment configured to bedeployed in the ipsilateral iliac artery and a second segment configuredto be deployed in the contralateral iliac artery. The first and secondsegments are self-expanding and further configured to be delivered in alinearized arrangement within a lumen of a delivery catheter and to bereleased from the delivery catheter to assume a nonlinear configurationover the carina with an opening directed at an aorta which branches intothe iliac arteries.

In specific embodiments, the first and second segments of the tubularprosthesis may each comprise self-expanding metal or polymer scaffolds,and each of the scaffolds is typically at least partially covered by agraft material, such as expanded PTFE, polyethylene membranes, and thelike. Exemplary tubular prostheses may have any of the specificgeometries described above in connection with the methods of the presentinvention.

In a further aspect of the present invention, delivery catheters fordelivering the tubular prostheses as described above will comprise acatheter body having a distal end and a proximal end. The tubularprosthesis is mounted over the catheter body at a location between thedistal and proximal ends so that the prostheses may be positioned overthe carina while the distal end of the catheter body extends out of acontralateral lumen while a proximal end of the catheter body remainsextending out of the ipsilateral lumen. The self-expanding tubularprosthesis is maintained on the stent by a sheath disposed coaxiallyover the catheter body to radially constrain both segments of thetubular prosthesis so that retraction of the sheath allows each segmentto expand within the respective iliac lumen.

The delivery catheter will be configured for delivery over a 0.035 inwire (0.040″ID) with an 8 Fr profile (0.104″ OD). The delivery catheterwill typically have a length of 120 cm for over the arch approach withan ipsilateral/contralateral sheath access) or a length of 75 cm forsingle side, ipsilateral access only. The prostheses will be configuredto accommodate iliac limb diameters from 6-12 mm, usually in 1 mmincrements and to accommodate aortic diameters from 12-24 mm in 2 mmincrements with an aortic portion extending 5-10 mm into the aorta andiliac limb lengths from 3-8 cm in 1 cm increments

In some cases, the sheath may comprise a single, continuous structurewhich at least partially covers both the distal and proximal segments ofthe tubular prosthesis. This way, the entire sheath may be retracted ina single direction to release both segments of the tubular prosthesissequentially. Alternatively and preferably, however, the sheath mayinclude at least a distal portion which at least partially covers thedistal or second (contralateral) segment of the tubular prosthesis and aproximal segment which at least partially covers the proximal (oripsilateral) segment of the tubular prosthesis. The distal portion maythen be used to distally retract the distal or second segment of thetubular prosthesis while the proximal portion may be retracted torelease the proximal or second segment of the tubular prosthesis. Use ofsuch a two-part release sheath has the advantages described above withconnection to the methods of the present invention. In yet anotheraspect of the present invention, a guidewire capture catheter comprisesa catheter body having a distal end and a proximal end. An expandableguidewire capture element is disposed on the catheter body, typicallynear the distal end thereof. The guidewire capture element is configured(1) to be expanded from a small-diameter configuration which permitsadvancement through an ipsilateral iliac arterial lumen to a space abovea carina to a large diameter configuration and (2) to deflect andcapture a guidewire emerging from a subintimal passage around anocclusion in a contralateral iliac arterial lumen.

The capture catheters of the present invention will be specificallydimensioned and configured to deploy the expandable guidewire captureelement within the lower region of the aorta immediately above thecarina and the branching into the right and left iliac arteries. Inparticular, a catheter will typically have a length in the range from 60cm to 90 cm, preferably being about 75 cm, and a 7 Fr for delivery overa 0.035 in guidewire. The expandable guidewire capture element will havea diameter when collapsed in the range from 1.5 mm to 2.5 mm, preferablybeing about 2 mm, and a diameter when fully expanded in the range from14 mm to 28 mm.

The guidewire capture catheter will be specifically configured so thatit may be advanced through a sheath into a contralateral femoral lumenand further through the contralateral iliac lumen, to the space abovethe carina for deployment of the catheter element. The capture elementitself may have any of the configurations discussed generally above. Ina still further aspect of the present invention, a system for deployinga prosthesis over a carina between an ipsilateral iliac lumen and acontralateral iliac lumen comprises a guidewire, a guidewire capturecatheter, a self-expanding tubular prosthesis, and a delivery catheter.The guidewire will be sized and be sufficiently stiff to be placedthrough an entry sheath into a femoral artery, over a carina at anaortic bifurcation, and out through an exit sheath in a contralateralfemoral artery. The guidewire capture catheter will comprise a catheterbody, having an expandable guidewire capture element for the distal endthereof. The self-expanding tubular prosthesis will have a first segmentconfigured to be deployed in the ipsilateral iliac lumen, and a secondsegment configured to be deployed in the contralateral iliac lumen. Thedelivery catheter will comprise a catheter body, having a proximal endand a distal end and a retractable sheath. The tubular prosthesis ismounted over the catheter body in a radially constrained configurationbeneath the retractable sheath, so that retraction of the sheath allowsboth segments of the tubular prosthesis to expand within the ipsilateraland contralateral iliac lumens, respectively.

The guidewire preferably has a length in the range from 200 cm to 300 cmand a diameter in the range from 0.8 mm to 1 mm. Further specificaspects of the guidewire capture catheter, the self-expanding tubularprosthesis, and the delivery catheter have been described above withrespect to other aspects of the methods and systems of the presentinvention.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIGS. 1A and 1B illustrate an aortic bifurcation into iliac brancharteries showing partially occlusive disease (FIG. 1A), and totallyocclusive disease (FIG. 1B).

FIG. 2 illustrates a prior art method for treating occlusive disease atan aortic bifurcation using “kissing” stents.

FIG. 3 shows an exemplary placement of a folded or bent tubularprosthesis constructed in accordance with the principals of the presentinvention providing an open area in the lower aorta which is generallyfree from structure and allows contralateral access of a guidewire andtreatment catheter for contralateral access of a guidewire and atreatment catheter for treatment of future disease which may occur at ornear the aortic bifurcation.

FIGS. 3A and 3B illustrate a first exemplary tubular prosthesisconstructed in accordance with the principals of the present inventionhaving a hinged region between first and second segments thereof.

FIGS. 4A and 4B illustrate a similar hinged tubular prosthesis to thatshown in FIGS. 3A and 3B but further having curved or arcing ends ofeach of the first and second segments which overlap when the tubularprosthesis is in a linearized configuration (FIG. 4A) and which open toprovide additional wall coverage of the aorta as shown in FIG. 3 .

FIGS. 5A and 5B illustrate a further exemplary embodiment of a tubularprosthesis constructed in accordance with the principals of the presentinvention having first and second segments joined by a short tether.

FIGS. 6A and 6B illustrate yet a further embodiment of a tubularprosthesis constructed in accordance with the principals of the presentinvention where the prosthesis includes first and second segments whichare unattached.

FIGS. 7A and 7B illustrate yet a further embodiment of a tubularprosthesis constructed in accordance with the principals of the presentinvention where the prosthesis comprises the tubular body having a holeor fenestration on one side thereof.

FIG. 8 illustrates an exemplary guidewire capture catheter constructedin accordance with the principals of the present invention.

FIGS. 9 and 10 illustrate alternative guidewire capture elements whichcan be employed on the guidewire capture catheters of the presentinvention.

FIG. 11 illustrates an exemplary prosthesis delivery catheterconstructed in accordance with the principals of the present invention.

FIGS. 12 and 13 illustrate the retraction of a single sheath to releasethe tubular prosthesis from the catheter of FIG. 11 .

FIG. 14 illustrates an alternative sheath structure for the prosthesisdelivery catheter of the present invention.

FIGS. 15 and 16 illustrate the retraction in opposite directions of twoportions of the sheath to release a prosthesis therefrom.

FIGS. 17-26 illustrate delivery of a tubular prosthesis over a carina inan aortic bifurcation in accordance with the principals of the methodsof the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring again to FIG. 3 , an exemplary tubular prosthesis 10constructed in accordance with the principals of the present inventionwill comprise a tubular body having a first segment 12 and a secondsegment 14. For convenience, as shown here and after, the first segment12 will be placed in the ipsilateral iliac artery IIA, which is theartery through which the crossing guidewire is to be placed. The secondsegment 14 will be placed in the contralateral iliac artery CIA which isthe iliac artery through which the guidewire capture catheter is to beadvanced and the crossing guidewire is eventually to be pulled back bythe guidewire capture catheter. The tubular prosthesis, when deployed asshown in FIG. 3 , will usually have a connecting region 22 whichbendable connects the first segment 12 to the second segment 14 at alltimes, including when the tubular prosthesis 10 is linearized orstraightened for delivery (not shown in FIG. 3 ) and when the prosthesisis bent and fully deployed with the connecting region 22 draped ortented over the carina C as shown in FIG. 3 .

Exemplary embodiments of the tubular prosthesis 10 are shown in FIGS. 3Athrough 7B. FIGS. 3A and 3B illustrate tubular prosthesis 10A having afirst segment 12A connected to a second segment 14A by a hinge region22A. As shown in FIG. 3B, the hinge region 22A can accommodate bendingof the prosthesis and will generally lie over the carina C (FIG. 3 )when the stent is deployed. Other features of the tubular prosthesis 10Ainclude a structure comprising and underlying scaffold 16, typically aresilient metal scaffold of the type commonly employed in vascular andnon-vascular stents and grafts. Exemplary materials included springstainless steel and Nitinol®. This scaffold 16 will typically be coveredby a graft material which can be any conventional or non-conventionalgraft material utilized in vascular and non-vascular medical procedures.Exemplary graft materials include expanded PTFE, polyethylenes, and thelike. Each of the tubular prostheses 10B-10E described below willusually have a similar structure including an inner scaffold and anouter graft cover.

The inner ends 20A of each of the first and second segments 12A and 14Aare shown to be straight and disposed laterally across the prosthesis10A when the prosthesis is in its linearized configuration. These ends20A will open into a V-shaped geometry when the stent is folded or bentas shown in FIG. 3B.

The tubular prosthesis 10B of FIGS. 4A and 4B is very similar to that ofthe prosthesis of FIGS. 3A and 3B. First segment 12B is joined to secondsegment 14B by a hinge region 22B. The inner edges 20B of the twosegments, however, differ in that they are curved inwardly and overlapwhen the prosthesis 10B is in its linearized or straightenedconfiguration as shown in FIG. 4A. When the prosthesis 10B is opened bybending or folding, as shown in FIG. 4B, the edges 20B of the first andsecond prosthesis segments open into a smooth and a continuous arcuateprofile similar to that shown in FIG. 3 . By curving the ends of theprosthesis segments, the effective coverage on the aortic walls can beincreased relative to that provided by the straight end segments 20A ofprosthesis 10A. It will be appreciated that other end geometries couldbe employed to both increase and decrease the coverage of the aorticwall by inclining, curving, or otherwise modifying the shape of theinterior ends of the first and second prosthesis segments. Othergeometries include castellated ends, zig-zag ends, serpentine ends, andthe like.

Referring now to FIGS. 5A and 5B, a tubular prosthesis 10C includes afirst segment 12C and a second segment 14C joined together by a tetherregion 22C. The tether 22C can be formed as a part of the underlyingscaffold (not shown) or could be later joined to previously manufacturedscaffold segments. The tether can bend at its middle, as shown in FIG.5B, which case the segments 12C and 14C would be generally symmetricallyplaced in the ipsilateral and contralateral iliac arteries. Using atether 22C, however, allows the bend point to be shifted which in turnallows a symmetric positioning of the first and second segments in theipsilateral and contralateral iliacs or other lumens, respectively. Theability to provide such repositioning allows improved treatment ofasymmetric diseases in the affricated lumens. The ability to move theedges 20C away from the Carina also allows a user to minimize coverageof the aortic wall should that be desired. Referring now to FIGS. 6A and6B, in some instances it may be desirable to have no connecting regionbetween a first prosthesis segment 12D and a second prostheses segment14D. In those instances, the segments may be oriented to accommodate thebifurcation, as shown in FIG. 6B, using the delivery systems of thepresent invention. Generally, however, it will be preferred to usesegments which are joined together by a hinge region, tether, or othercoupling structure. In other instances, the first and second segmentsmay be deployed in an unconnected manner and it will be possible tosubsequently introduce a connecting region to help pull the relativepositions of the segments.

Referring now to FIGS. 7A and 7B, a tubular prosthesis 10E comprises agenerally continuous tubular structure 24 having a first segment 26 anda second segment 28. The first and second segments are defined by thepresence of an opening or fenestration 30 which will be sized to open toa diameter (as shown in FIG. 7B) which corresponds at least generally tothe aortic diameter immediately above the Carina. The scaffold structureof the prosthesis 10E will allow the opening 30 to expand and the closedportion of the tubular body 24 to bend into an arc 32, as shown in FIG.7B. The tubular prosthesis 10E may be delivered by the delivery systems,as described hereinafter, that will generally not be preferred over thehinged, tethered, or similarly coupled structures described previously.

Referring now to FIG. 8 , an exemplary guidewire capture catheter 40comprises a catheter body 42 having an inner tubular member 44 and anouter tubular member 46. The inner and outer tubular members arearranged coaxially and can axially slide relative to each other in orderto deploy an expandable guidewire capture element 48, as described inmore detail below. The expandable guidewire capture element is disposedgenerally at a distal end 50 of the catheter body and a deploymenthandle assembly 52 is disposed at a proximal end 54 of the catheterbody. Usually, an atraumatic tip 56 extends beyond the distal end of theexpandable guidewire capture element 48 in order to minimize traumawhich could occur if the somewhat rigid capture element were at the tipof the catheter 50. The guidewire capture catheter will be configured tobe advanced over a Guidewire followed by reference letters GW, with theguidewire generally passing through an interluminar passage of the innertubular member 44 and not shown). The guidewire capture element 48 isshown in its low profile or radially collapsed configuration in solidline in FIG. 8 . The capture element 48 may be radially expanded intothe configuration shown in broken line in FIG. 8 by pushing pusher 48 ofthe handle assembly relative to a grip 60 at the end of the outertubular member 46. Pushing the pusher advances the distal end of theinner tubular member 44 which is connected to a proximal end of theexpandable guidewire capture element 48. As the distal end 64 of thecapture element is attached to the inner tubular member, the captureelement is axially foreshortened which forces the radial expansion.

As illustrated in FIG. 8 , the expandable guidewire capture element 48comprises a plurality of axial elements circumferentially distributedover the catheter body 42. Each linear element has weakened regionswhich preferentially bend when the capture element is actuallyforeshortened. As illustrated, each individual element 66 has a pair ofweakened regions which result in a generally U-shaped expandedstructure. As described hereinafter with respect to the method, such anexpanded cage structure will both place radially expansive forcesagainst the aortic or other lumenal wall in which they are extended.Such expansion force will assist in guidewire exit when the guidewire isbeing advanced subintimally. Additionally, after the guidewire exits andpasses through the expanded guidewire capture element, the captureelement may be collapsed to capture the guidewire and allow theguidewire to be drawn out through the contralateral lumen as the capturecatheter is withdrawn.

Referring to FIGS. 9 and 10 , the expandable guidewire capture elementmay have a variety of specific implementations. As shown in FIG. 9 ,instead of discreet axial elements which fold upon foreshortening, analternative capture element 48A may comprise a polymeric braidedstructure which will regularly expand into a generally disk geometry(shown in broken line) when the inner tube 44 and outer tube 46 areclosed together.

A further exemplary alternative as shown in FIG. 10 where an expandableguidewire capture element 48B comprises a balloon 68 optimally coveredby a lattice structure 70 which can expand with the balloon. The balloonand lattice are show in their full expanded configurations in full lineand their expanded configurations in broken line. The presence of thelattice 70, which can generally have a stent-like pattern orrestructure, can provide a more positive transmission of force to theaortic or other wall in which the capture element is being expanded.Additionally, the lattice can help capture a guidewire which is advancedto the capture element

Referring now to FIGS. 11-13 , a first exemplary delivery catheterconstructed in accordance with the principles of the present inventionwill be described. The delivery catheters are intended to deliver thetubular prosthesis described previously into and over a Carina in orderto stent or graft regions of the branching vessels on either side of theCarina. The first delivery catheter embodiment 80 comprises a catheterbody 82 having a distal end 84 and a proximal end 86. A handle or hub 88is disposed at the proximal end 86 of the catheter body and a guidewireport 90 is provided at the distal end 84. Catheter 80 will be configuredfor advancement over the crossing guidewire which has been placed fromthe ipsilateral lumen to the contralateral lumen over the Carina as willbe described below.

The retractable sheath 92 is coaxially mounted over the catheter body 82and has a sheath handle 94 which allows the retraction of the sheathrelative to the catheter body. The tubular prosthesis 12 (FIGS. 12 and13 ) is initially maintained beneath a distal end or portion of theretractable sheath 92 where it remains as the catheter is being advancedover the guidewire to the region over the Carina. The sheath 92 may bethen be proximally retracted, as shown in FIG. 12 , so that the firstsegment 12 of the tubular prosthesis is released and begins toself-expand at the desired location. Continued retraction of the sheath92, as show in FIG. 13 , results in full release of the prosthesis 10,including both the first segment 12 and the second segment 14, as shownin FIG. 13 . Complete deployment of the tubular prosthesis will, ofcourse, occur when the catheter body 82 is retracted from within theinterior of the prosthesis. Additionally, of course, the guidewire willalso be fully retracted but the guidewire will generally not inhibit theprosthesis from fully bending and folding within the target anatomy.

Referring now to FIGS. 14-16 , a second exemplary embodiment of thedelivery catheter 100 constructed in accordance with the principles ofthe present invention will be described. The delivery catheter 100includes a catheter body 102 which is preferably divided into anipsilateral portion 102A and a contralateral portion 102B. The deliverycatheter will further comprise a sheath 104 which is also divided intoan ipsilateral portion 104A and a contralateral portion 104B. Thetubular prosthesis 10 was initially constrained by the sheath assemblywith a full width ipsilateral portion 104A covering the first segmentprobe of the stent and the contralateral portion 104B covering thesecond segment 14 of the prosthesis. Other than that shown in FIGS.14-16 , it will be appreciated that the sheath portions 104A and 104Bwill meet at a point which is generally in the middle of the catheter100 and catheter body 102 so that the catheter may be deployedcompletely from the entry sheath in the ipsilateral lumen to the exitsheath and the contralateral lumen. Each sheath will be accessibleexternal to the patient so that the sheaths may be retracted to deploythe tubular prosthesis 10, generally as shown in FIG. 15 and FIG. 16 .

The tubular prosthesis 10 will usually include radiopaque markers 106near its middle and in each end to facilitate positioning of the stentat the desired location over the carina C of the bifurcated lumens.Alternatively or additionally, the depict markers could be provided onthe sheath and/or the catheter body.

Retracting the ipsilateral sheath portion 104A toward the ipsilateralvasculature and retracting the contralateral sheath portion 104B towardthe contralateral vasculature will result in a symmetric release of thetubular prostheses as shown in FIGS. 15 and 16 .

While it would be possible to deliver the sheath in this way using acontinuous catheter body 102 which would remain within the tubularprosthesis 10, such deployment would require that the catheter body beseparately withdrawn from within the tubular prosthesis in order toallow the prosthesis to fully deploy. Thus, in many embodiments, it willbe preferred to provide the catheter body 102 as a separate ipsilateralportion 102A and contralateral portion 102B. In this way, the separateportions of the catheter body 102 may also be separately retracted inipsilateral and contralateral directions from within the tubularprosthesis in order to permit full deployment of the tubular prosthesis,as shown in FIG. 16B. In such embodiments, ipsilateral components of thedelivery catheter 100 will eventually be withdrawn through theipsilateral access sheath or contralateral portions of the deliverycatheter will be withdrawn through the contralateral access sheath.

Referring now to FIGS. 17-26 , delivery of the tubular prosthesis 10 ofthe present invention in accordance with an exemplary method of thepresent invention will be described. Initially, as shown in FIG. 17 , acrossing guidewire 110 is placed into the ipsilateral iliac artery IIAthrough an access sheath 114. The crossing guidewire is advanced untilit reaches a downstream side of a chronic total occlusion. A second,contralateral guidewire 112 is advanced into the contralateral iliacartery CIA through an access sheath 116 and advanced typically until itreaches the aorta A.

As shown in FIG. 18 , the guidewire capture catheter 40 is then advancedthrough the access sheath 116 over the contralateral guidewire 112 toposition the expandable guidewire capture element 48 in the aorta in aregion above the Carina and near the upstream side of the Chronic totalOcclusion.

As shown on FIG. 19 , the expandable guidewire capture element has beenradially expanded so that it engages the aortic wall circumferentiallyalong the line generally aligned with the upstream side of the chronictotal occlusion. The expanded guidewire capture element implies anexpansive force against the aortic wall, and in particular providestension and a backstop along the upstream side of the chronic totalocclusion CTO.

After deployment of the expandable guidewire capture element 40, thecrossing guidewire 110 may be advanced past the chronic total occlusionCTO as shown in FIG. 20 . Typically, the crossing guidewire 110 willfollow a sub intimal path SIP, where the engagement of the captureelement 48 facilitates reentry of the crossing guidewire 110 into theaortic lumen, as illustrated. Not only does the expanded guidewirecapture element 48 facilitate reentry of the crossing guidewire, theelement can also capture a distal end of the guidewire, as will bedescribed with reference to FIG. 21 .

As shown in FIG. 21 , the expandable guidewire capture element 48 may becollapsed over the guidewire to firmly engage the guidewire so that thecatheter may be used to pull the guidewire over the carina C. Bycompletely withdrawing the guidewire capture catheter 40 from thecontralateral iliac aorta and through the access sheath 116, as shown inFIG. 22 , the crossing guidewire 110 will be deployed to cross thecarina C with one end accessible through the ipsilateral access sheath114 and the other end accessible through the contralateral access sheath116. Optionally, the contralateral guidewire 112 may be left in place toestablish further access if needed. For convenience, the contralateralguidewire 112 will not be shown in the remainder of the figures.

As show in FIG. 23 , optionally a pre-shaped guide catheter 120 may beadvanced through the ipsilateral access sheath over the guidewire todefine a path through or past the chronic total occlusion CTO.

Either with or without the guide catheter, a prosthesis deliverycatheter may then be introduced using the previously placed crossingguidewire 110. As shown in FIG. 24 , the delivery catheter 100 which hasa pair of sheath portions 104A and 104B is used for this example. Afterpositioning the delivery catheter 100 over the carina C, the ipsilateralsheath portion will be accessible through the ipsilateral access sheath112 and the contralateral sheath portion 104B will be available throughthe contralateral access port 116. The access sheaths may then bewithdrawn in ipsilateral and contralateral directions, respectively,allowing the tubular prosthesis segments 12 and 14 to radially expand insitu, as shown in FIG. 25 . As shown in FIG. 25 , the catheter body 102of the delivery catheter is a single element and will remain in placeafter the tubular prosthesis has radially expanded.

The catheter body 102 may be withdrawn through either of the accesssheaths 112 or 116, the crossing guidewire in place. The crossingguidewire can also be withdrawn, leaving the fully deployed prosthesis110 in place with the first segment 112 in the Ipsilateral Iliac Arteryin the second segment 14 present in the Contralateral Iliac Artery. Thestent deploys with the hinge region 22 over the carina C.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

What is claimed is:
 1. A delivery catheter system comprising: aself-expanding tubular prosthesis having a side opening and configuredto be delivered in a linearized arrangement and draped over a deliverybody to assume a non-linear configuration over a patient's carina toposition the opening at an aorta where the aorta branches into theipsilateral and contralateral iliac arteries; and a catheter body havinga distal end and a proximal end, wherein the self-expanding tubularprosthesis is mounted over the catheter body so that the prosthesis maybe positioned over the carina with a distal portion of the catheter bodyin the contralateral artery and a proximal portion of the catheter bodyin the ipsilateral artery; and a sheath configured to be disposedcoaxially over the catheter body to radially constrain theself-expanding tubular prosthesis in the linearized arrangement so thatretraction of the sheath allows the tubular prosthesis to expand withthe opening centered at the aorta.
 2. A delivery catheter system as inclaim 1, wherein the tubular prosthesis comprises a self-expanding metalscaffold.
 3. A delivery catheter system as in claim 2, wherein theself-expanding metal scaffold is covered by a graft material.
 4. Adelivery catheter system as in claim 1, wherein the self-expandingtubular prosthesis has a hinge region in a middle region thereof alignedwith the opening.
 5. A delivery catheter system as in claim 4, whereinthe hinge region comprises a tether.
 6. A delivery catheter system as inclaim 1, wherein the tubular prosthesis comprises separate, unjoinedsegments.
 7. A delivery catheter system as in claim 1, wherein thesheath includes a distal portion which at least partially covers adistal segment of the tubular prosthesis and a proximal segment which atleast partially covers a proximal segment of the tubular prosthesis,wherein the distal portion may be retracted distally to release thedistal segment and the proximal portion may be retracted proximally torelease the proximal segment.
 8. A delivery catheter system as in claim1, wherein the sheath comprises a single, continuous structure which atleast partially covers both distal and proximal segments of the tubularprosthesis so that the entire sheath may be retracted in a singledirection to release both segments of the tubular prosthesis.